public class Example3_6{
    public static void main (String args[]) {
        double sum = 0,item = 1;
        int i = 1,n = 20;
        while(i<=n) {
                sum = sum+item;
                i = i+1;
                item = item*(1.0/i);
        }
        System.out.println("sum="+sum);
    }
}